Electrical machine and an electrical power generating system

• US 6,919,711 B2
• Filed: 09/19/2002
• Issued: 07/19/2005
• Est. Priority Date: 09/19/2001
• Status: Active Grant

• Current Assignee: Cummins Generator Technologies Limited (Cummins Incorporated)
• Original Assignee: Newage International Ltd (Cummins Incorporated)
• Inventors: Koczara, Wlodzimierz, Al-Khayat, Nazar, Haydock, Lawrence
• Primary Examiner(s): Ponomarenko, Nicholas
• Assistant Examiner(s): Mohandesi, Iraj A.
• Application Number:
  US10/489,873
• Publication Number:
  US 20040251881A1
• Time in Patent Office: 1,034 Days
• Field of Search: 322/24, 322/28, 322/25, 322/22, 322/20, 322/46, 322/19, 323/29, 363/95, 363/50
• US Class Current: 322/24
• CPC Class Codes: B60L 2210/30 AC to DC converters
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator
• CPC Class Codes: H02P 9/307 more than one voltage output
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A generating set includes an engie driven generator (PGM) having two sets of stator windings (Ga and Gb). A bi-directional AC/DC converter (BCo) has its AC input connected to a junction between the two sets of stator windings (Ga and Gb) and its DC input connected to a number of the generator (PGM) is converted into an intermediate DC link by a convertor (Col) to produce an output for a load Lo. In normal operation of the system, an emf generated in one (Ga) of the sets of stator windings is rectified by the bi-direcitonal converter (BCo) to charge the energy storages (ESI-ESN) whilst the remainder of the generator output is fed through the converter to the load (Lo). In the event of a stepped increase in the load demand, the bi-directional converter (BCo) is operated to feed energy from the storage devices (ESI-ESN) to the stator windings (Ga) of the generator (PGM) to impart a driving torque to the generator rotor to accelerte the rotor to meet the increased load demand. The energy stored in the storages devices (ESI-ESN) could be used to start the engine (EN).

Claims

1. An AC electrical machine including a rotor, a stator and two sets of windings on the stator in which an emf is induced by rotation of the rotor, one of the two sets of windings on the stator being connected to a chargeable source of electrical potential, said AC electrical machine further including control means operable to effect operation of the AC electrical machine in one of two modes, the AC electrical machine being operable in one of the two modes to rectify an electrical potential generated by induction of an emf in said one set of windings and to conduct the rectified electrical potential to charge the chargeable source, wherein said one set of windings is connected to said chargeable source of electrical potential through bi-directional AC/DC conversion means and said control means are operable to effect operation of said bi-directional AC/DC conversion means in a respective one of two modes for each of said two modes of operation of the AC electrical machine, the bi-directional AC/DC conversion means being operable in said one mode of operation of the AC electrical machine to effect said rectification of the electrical potential to charge the chargeable source, and in the other mode to invert the electrical potential of the chargeable source into an AC potential and to apply that AC potential to said one set of windings whereby to produce a rotating magnetic field around the rotor and thereby to apply a driving torque to the rotor, to accelerate the rotor in response to an increase in load demand on the AC electrical machine, the emf induced in the other set of windings being available to meet a load demand on the AC electrical machine during both modes of operation of the AC electrical machine and during said other mode of operation of the AC electrical machine, to do so in combination with the emf induced in said one set of windings.

2. An AC electrical machine according to claim 1, wherein said chargeable source of electrical potential is one of a plurality of such chargeable sources of electrical potential which each include an energy storage and which are each equipped with respective conversion means which are operable to assure bi-directional transmission of electrical potential between the respective energy storage and a DC output of the bi-directional AC/DC conversion means.

3. An AC electrical machine according to claim 2, wherein each said conversion means includes a charging transistor and a discharging transistor and said control means are operable to activate the charging transistors and to deactivate the discharging transistors for said one mode and to activate said discharging transistors and to deactivate said charging transistors for said other mode.

4. An AC electrical machine according to claim 1, wherein the bi-directional AC/DC conversion means is a 3-phase transistor converter.

5. An AC electrical machine according to claim 1, wherein said one set of windings are connected in series with said other set of windings on the stator and an AC output of said bi-directional AC/DC conversion means is connected to a junction between said one set of windings and said other set of windings.

6. An electrical power generating system of the kind which includes generator means operable to generate a variable voltage generator output, a variable speed prime mover drivingly coupled with the generator means, speed control means operable to control the speed of the prime mover, converter means operable to establish an intermediate DC link by converting the variable voltage generator output into an intermediate DC voltage and to convert the intermediate DC voltage to an electrical power output for supply to an external load, sensing means operable to monitor the intermediate DC link when the load is connected across the intermediate DC voltage and to provide a feedback signal to the speed control means whereby to effect variation of the variable voltage electrical output and thereby to counter a tendency of the intermediate DC voltage to vary wherein the generator means is an AC electrical machine including a rotor, a stator and two sets of windings on the stator in which an emf is induced by rotation of the rotor, one of the two sets of windings on the stator being connected to a chargeable source of electrical potential and control means operable to effect operation of the AC electrical machine in one of two modes are provided, the AC electrical machine being operable in one of the two modes to rectify an electrical potential generated by induction of an emf in said one set of windings and to conduct the rectified electrical potential to charge the chargeable source, said one set of windings being connected to said chargeable source of electrical potential through bi-directional AC/DC conversion means and said control means being operable to effect operation of said bi-directional AC/DC conversion means in a respective one of two modes for each of said two modes of operation of the AC electrical machine, the bi-directional AC/DC conversion means being operable in said one mode of operation of the AC electrical machine to effect said rectification of the electrical potential to charge the chargeable source, and in the other mode to invert the electrical potential of the chargeable source into an AC potential and to apply that AC potential to said one set of windings whereby to produce a rotating magnetic field around the rotor and thereby to apply a driving torque to the rotor, to accelerate the rotor in response to an increase in load demand on the AC electrical machine, the emf induced in the other set of windings being available to meet a load demand on the AC electrical machine during both modes of operation of the AC electrical machine and during said other mode of operation of the AC electrical machine, to do so in combination with the emf induced in said one set of windings.

7. An electrical power generating system according to claim 6 in which said chargeable source of electrical potential is one of a plurality of such chargeable sources of electrical potential which each include an energy storage and which are each equipped with respective conversion means which are operable to assure bi-directional transmission of electrical potential between the respective energy storage and a DC output of the bi-directional AC/DC conversion means, wherein an energy storage device of one of the chargeable sources of electrical potential includes one or more batteries which are a source of energy for starting the prime mover.

8. An electrical power generating system according to claim 7 wherein the energy storage device of at least one of the chargeable sources of electrical potential includes at least one capacitor and said control means are operable to effect discharge thereof in said other mode to cater for one of transient variations in the external load demand and starting said prime mover.

9. An electrical power generating system according to claim 6, in which said chargeable source of electrical potential is one of a plurality of such chargeable sources of electrical potential which each include an energy storage and which are each equipped with respective conversion means which are operable to assure bi-directional transmission of electrical potential between the respective energy storage and a DC output of the bi-directional AC/DC conversion means and each said conversion means includes a charging transistor and a discharging transistor and said control means are operable to activate the charging transistors and to deactivate the discharging transistors for said one mode and to activate said discharging transistors and to deactivate said charging transistors for said other mode, wherein an energy storage device of one of the chargeable sources of electrical potential includes one or more batteries which are a source of energy for starting the prime mover.

10. An electrical power generating system according to claim 6 in which said chargeable source of electrical potential is one of a plurality of such chargeable sources of electrical potential which each include an energy storage and which are each equipped with respective conversion means which are operable to assure bi-directional transmission of electrical potential between the respective energy storage and a DC output of the bi-directional AC/DC conversion means, wherein an energy storage device of one of the chargeable sources of electrical potential includes a source of power for energizing control units of the generating system.

11. An electrical power generating system according to claim 10 wherein the energy storage device of at least one of the plurality of chargeable sources of electrical potential includes at least one capacitor and said control means are operable to effect discharge thereof in said other mode to cater for one of transient variations in the external load demand and starting said prime mover.

12. An electrical power generating system according to claim 6, in which said chargeable source of electrical potential is one of a plurality of such chargeable sources of electrical potential which each include an energy storage and which are each equipped with respective conversion means which are operable to assure bi-directional transmission of electrical potential between the respective energy storage and a DC output of the bi-directional AC/DC conversion means and each said conversion means includes a charging transistor and a discharging transistor and said control means are operable to activate the charging transistors and to deactivate the discharging transistors for said one mode and to activate said discharging transistors and to deactivate said charging transistors for said other mode, wherein an energy storage device of one of the chargeable sources of electrical potential includes a source of power for energizing control units of the generating system.

13. An electrical power generating system according to claim 6 in which said chargeable source of electrical potential is one of a plurality of such chargeable sources of electrical potential which each include an energy storage and which are each equipped with respective conversion means which are operable to assure bi-directional transmission of electrical potential between the respective energy storage and a DC output of the bi-directional AC/DC conversion means, wherein an energy storage device of at least one of the chargeable sources of electrical potential includes at least one capacitor and said control means are operable to effect discharge thereof in said other mode to cater for one of transient variations in the external load demand and starting said prime mover.

14. An electrical power generating system according to claim 6, in which said chargeable source of electrical potential is one of a plurality of such chargeable sources of electrical potential which each include an energy storage and which are each equipped with respective conversion means which are operable to assure bi-directional transmission of electrical potential between the respective energy storage and a DC output of the bi-directional AC/DC conversion means and each said conversion means includes a charging transistor and a discharging transistor and said control means are operable to activate the charging transistors and to deactivate the discharging transistors for said one mode and to activate said discharging transistors and to deactivate said charging transistors for said other mode, wherein an energy storage device of at least one of the chargeable sources of electrical potential includes at least one capacitor and said control means are operable to effect discharge thereof in said other mode to cater for one of transient variations in the external load demand and starting said prime mover.

15. An electrical power generating system according to claim 6 in which said one set of windings are connected in series with said other set of windings on the stator and an AC output of said bi-directional AC/DC conversion means is connected to a junction between said one set of windings and said other set of windings, wherein said control means is operable to disenable said bi-directional AC/DC conversion means whilst the intermediate DC voltage is being increased to a certain level after starting.